(a) Field of the Invention
This invention relates to substituted 3H-imidazo[4,5-b]pyridines, their preparation and their use as cardiotonics.
(b) Description of the Prior Art
Baldwin et al. [J. Med. Chem. 20, 1189-1193 (1977)] disclose the preparation of 2-(3-pyridinyl)-1H-imidazo[4,5-b]pyridine and 2-(4-pyridinyl)-1H-imidazo[4,5-b]pyridine by heating, respectively, a mixture of 2,3-diaminopyridine and nicotinic acid and a mixture of 2,3-diaminopyridine and isonicotinic acid. Both of these compounds were reported by Baldwin et al. to be inactive when tested as inhibitors of xanthine oxidase.